Coordinated multi-point transmission and reception for mobile networks involves communication with a single mobile device or user equipment (UE) from a plurality of network elements. A network element may be a base station, an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) node B (eNB), a cell within an eNB or other types of network node. For example, in Long Term Evolution-Advanced (LTE-A), coordinated multi-point transmission and reception will be supported. For uplink transmission, when the UE sends packets to both a first and a second network element, if either network element correctly receives the packet from the UE, then the packet is considered to be successfully received.
In Hybrid Automatic Repeat Request (HARQ) systems, the UE transmits one HARQ transmission in a time period, and upon receiving a negative acknowledgement from a network element, the UE transmits a second or subsequent HARQ transmission in a subsequent time period.
When two network elements related to the base stations receive a packet, they each attempt to decode the packet. However, in order for the network elements to properly coordinate, the packet status needs to be communicated between the two network elements. This handshaking occurs over a backhaul link and in order for the uplink coordinated multi-point transmissions to properly operate, the handshaking on the backhaul link must occur. Under current HARQ systems, the time required for this backhaul link signaling may be insufficient to properly coordinate the network elements.